Turley, Tamiel Nichole

Abstract Gastrointestinal (GI) cancers are rising in people < 50 and remain major causes of cancer mortality despite therapeutic advances. Chimeric antigen receptor T (CART) cell therapy has transformed treatment of hematological cancers. However, its efficacy in GI cancers has been hindered by antigen heterogeneity and immunosuppressive cancer associated fibroblasts (CAFs) in the tumor microenvironment (TME.) Here we aimed to 1) study CART-CAF interactions and 2) engineer CART cells capable of eliminating CAFs to overcome their inhibitory role and enhance their antitumor activity in GI cancers. We first analyzed primary CAFs from 20 GI cancer patients. CAFs showed high fibroblast activation protein (FAP) expression and significantly suppressed T cells proliferation (26-77%, p≤0.0001). We next generated CART cells capable of safely eliminating both GI cancer cells and CAFs. To target cancer cells, we developed a novel nanobody (VHH)-based CAR against Claudin18.2, a GI cancer specific target. To avoid off-tumor toxicity in healthy FAP+ tissues, we incorporated an inducible FAP-CAR using the synNotch platform, enabling conditional targeting upon engagement with Claudin18.2+ cells, restricting FAP targeting within the TME. VHH Claudin18.2 CART cells showed superior specificity and efficacy vs scFv-based CART cells (hu8E85 or zolbetuximab). In Claudin18.2+ SNU-C2B xenografts, tumors were 92mm3 (VHH) vs 48mm3 (huE85) vs 211mm3 (zolbetuximab) on day 23 post-CART, median survival undefined vs 17 days vs 23 days respectively; p=0005. In Claudin18.2+ LS411N xenografts, tumors were 315mm3 vs 106mm3 vs 382 mm3 respectively at 23 days post-CART, median survival undefined vs 19 days vs undefined respectively; p=0004. VHH Claudin18.2 CART cells showed no off-tumor effects, while hu8E85 CART induced significant toxicity. We next established a co-engraftment model. NSG mice received 1x106 SNU-C2B and 6x106 CAFs from a GI cancer patient. At 500 mm3 tumors, mice received 5x106 VHH Claudin18.2 or inducible Claudin18.2/FAP CART. Dual-targeting CART cells showed greater antitumor response (728mm3 vs 320mm3, p=0.0011 at day 20 post-CART), expansion (61 vs 2,350 CART/µl of blood, p=0.0037), and tumor infiltration (8.71 x 105 vs 1.03 x 106 CART/g of tumor, p<0.0001). This was also observed in gastric, colon, and pancreatic PDX models, with no observable off-tumor cytotoxic effects with inducible dual-targeting Claudin18.2/FAP CART. Our findings demonstrate that our novel VHH-based Claudin18.2 CART cells are highly specific and effective against GI malignancies, and that inducible Claudin18.2/FAP dual-targeting CART cells safely remodel the TME into an immune-permissive state. This approach represents a mechanistically innovative and translationally relevant strategy to overcome CAF-mediated immunosuppression, enhance CART cell efficacy, and improve clinical outcomes in refractory solid tumors. Citation Format: Omar L. Gutierrez Ruiz, Jennifer Feigin, Brooke Kimball, R. Leo Sakemura, Elizabeth L. Siegler, Dominic A. Skeele, Ateka Saleh, Claudia Manriquez Roman, Ismail Can, Olivia Sirpilla, Kun Yun, Carli M. Stewart, Mehrdad Hefazi, Yoh Yamaguchi, Lionel Aurelien Kankeu Fonkoua, Long K. Mai, Truc Huynh, Sophia Y. Goldberg, Grace E. DeFranco, Sara Foote, Ekene Johnkennedy Newton Ogbodo, Hong Xia, Michael Redig, Matthew L. Matthew, Tamiel Nichole Turley, Skyeler Klinge, John Alton Copland, Saad J. Kenderian. Optimized CART cell therapy to remodel the tumor microenvironment and eliminate GI malignancies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 1525.

Abstract Lipid metabolism plays an important role in lung cancer growth, survival, and therapeutic resistance. Stearoyl-CoA desaturase 1 (SCD1), the enzyme that converts saturated fatty acids (SFAs) into monounsaturated fatty acids (MUFAs), represents a metabolic vulnerability since cancer cells depend on MUFAs for membrane biosynthesis, ER homeostasis, and alternative energy to glucose. SSI-4 (a.k.a MTI-301) is a selective SCD1 inhibitor currently in Phase I clinical evaluation for metastatic, unresectable, or refractory solid cancers, but its activity in non-small cell lung cancer (NSCLC) has not yet been characterized. To evaluate how NSCLC models respond to SCD1 blockade, we performed an initial screen of a panel of 17 human non-small cell lung cancer cell lines treated with 100 nM SSI-4 under defined serum conditions. Cell viability assays identified 9 responding cell lines, and dose-response studies confirmed IC50 values ranging from approximately 0.65 to 45.5 nM. Rescue experiments showed that adding oleic acid, an SCD1 regulated MUFA, reversed SSI-4-mediated growth inhibition, confirming mechanistically that this effect occurs through SCD1 blockade. Western blot analysis confirmed that SSI-4 treatment increased markers of endoplasmic reticulum (ER) stress and apoptosis in sensitive lines, consistent with disruption of lipid homeostasis. In contrast, non-responsive lines exhibited minimal induction of these stress pathways and retained viability despite treatment. Soft agar assays further showed that SSI-4 reduced anchorage-independent colony formation in responsive lines, indicating that SCD1 inhibition suppresses a key malignant growth property in these NSCLC models. Collectively, these findings demonstrate that SSI-4 selectively inhibits proliferation in a subset of NSCLC cells through an SCD1-dependent mechanism by reducing MUFA availability and activating stress and apoptotic signaling. This work establishes a framework for subsequent in vivo studies and lays the foundation for exploring SCD1 inhibition as a potential therapeutic strategy for patients with limited treatment options in NSCLC, while also advancing understanding of the mechanisms by which SCD1 supports tumor survival. Citation Format: Valeria Romina Salerno Gonzales, Lauren Antal, Tamiel Nichole Turley, John A. Copland III. Inhibition of stearoyl-CoA desaturase 1 (SCD1) by SSI-4 as a therapeutic strategy in non-small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 2942.